From conception to a missed period: a day-by-day guide

Here’s what happens, step by step, between your fertile window and a missed period. The dates below are for a 28-day cycle. If your cycle is longer or shorter, ovulation (and everything after it) moves too. ‘DPO’ means days past ovulation, which is how many people track the two week wait.

The timeline

Cycle days 1 to 5: Your period

Pregnancy is dated from the first day of this period, so if you get pregnant this cycle you’ll already count as about 2 weeks pregnant when you conceive.

Cycle days 9 to 14: Your fertile window

You’re most fertile in the few days before ovulation and on the day itself. Sperm can live for up to 7 days inside your body, so sex during these days can lead to a pregnancy.

Day 14 (ovulation, 0 DPO): An egg is released

The egg travels into a fallopian tube. It can be fertilised for up to about a day. If a sperm reaches it, this is conception.

1 to 5 DPO: The journey to the womb

The fertilised egg divides into more and more cells as it moves down the tube. By about day 5 it’s a tiny ball of cells called a blastocyst, and it reaches the womb.

6 to 12 DPO: Implantation

The blastocyst attaches to the womb lining and buries into it, most often 8 to 10 days after ovulation. Some people notice light spotting or mild cramps; many notice nothing.

From implantation: hCG starts

The pregnancy starts making hCG, the hormone tests detect. It roughly doubles every couple of days at first.

From about 10 DPO: Very early testing

Some early tests can be used from 5 days before your period is due. They pick up some pregnancies this early, but not all.

Day 29, about 2 weeks after ovulation: Your period is due

If you’re pregnant, your period won’t come. You now count as 4 weeks pregnant. Most pregnancies will show on a test by now, but not all, so if it’s negative and your period still doesn’t come, test again a few days later.

If your cycle isn’t 28 days

Ovulation usually happens 10 to 16 days before your next period, not on a fixed day. So in a 35-day cycle you might ovulate around day 21, and everything above shifts about a week later. In a 24-day cycle it might be around day 10. If your cycles vary a lot, it’s harder to know when to test, so work out when your period is due using your longest recent cycle, or test at least 21 days after you last had unprotected sex.

How pregnancy weeks are counted

Pregnancy is counted from the first day of your last period, not from conception. That’s why you’re ‘2 weeks pregnant’ when you conceive and ‘4 weeks pregnant’ by the time you miss your period. Your due date is worked out the same way. If you know your conception date, our due date calculator can use that instead.

What you might notice along the way

Around ovulation: some people feel a twinge on one side (ovulation pain) or notice clear, stretchy discharge. Neither is a sign of pregnancy.
Around implantation: possible light spotting or mild cramps. Read more about implantation bleeding and implantation cramps.
Before your period is due: sore breasts, tiredness and bloating are common in every cycle, pregnant or not.
Around your missed period and after: this is when pregnancy symptoms like feeling sick usually start. See early signs of pregnancy.

When to test

Most pregnancy tests are designed to be used from the day your period is due. Test makers say they’re over 99% accurate from then, though that figure comes from lab testing. A positive result is almost certainly right, but a negative result is less reliable.

Some early tests can be used from 5 days before your period is due (the packet may call this ‘6 days before your missed period’), and some people do get a positive that early. One leading brand says that in lab testing, its most sensitive test picked up 78% of pregnancies at that point, and more the closer you get to your period.

A negative result can be wrong if there isn’t enough hCG yet, even on the day your period is due. Everyone ovulates and implants at a slightly different time, and one study found that on the day women expected their period, about 1 in 10 pregnancies hadn’t implanted yet, so no test could have found them. If you get a negative result and your period doesn’t come, wait a few days and test again. If it’s still negative and your period hasn’t arrived, speak to your GP.

Positive? Our first few weeks, step by step guide covers what to do next.

Questions people ask

How many days after sex can you get pregnant?

Conception can happen several days after sex, because sperm can survive for up to 7 days in your body. Implantation follows about a week after conception.

How soon after implantation can I test?

hCG starts once the pregnancy has implanted, but it takes a few days to rise high enough for a home test. Testing from the day your period is due gives the most reliable result.

What if a fertilised egg doesn’t implant?

It passes out of your body with your period, usually without you ever knowing. Sometimes a pregnancy implants but stops developing very early, which can cause a brief positive test before a period arrives.

When to get help

Mild cramps that ease with rest are usually nothing to worry about. But if you’re pregnant, or think you could be, get urgent advice from your maternity unit, an early pregnancy unit or NHS 111 if you have:

any bleeding or spotting, even if it’s light
tummy pain that’s severe, on one side, or hasn’t eased after resting for 30 to 60 minutes
pain in the tip of your shoulder

Call 999 if you have bleeding along with severe tummy pain, pain in your shoulder, or feeling sick, faint or dizzy, or if the bleeding is heavy (soaking a pad soon after putting it on). Also call 999 if you have sudden, sharp and intense tummy pain and you feel very dizzy or faint, feel sick or look very pale. These can be signs of an ectopic pregnancy or a miscarriage that need treating straight away.